Median refers to the value which lies in the middle of the data (when arranged in an increasing or decreasing order).
The temperatures are arranged in the increasing order as follows.
38, 40, 43, 46, 48
Here, n = 5
Median=(n+1)2th observation
=(5+1)2
=3rd observation
=43
Therefore, median temperature is 43∘C and it happens in the month of May.